The sinuses are hollow areas in the skull that are arranged in pairs. Sinusitis occurs when the tissue lining the sinuses in the skull around the nose (the paranasal sinuses) becomes inflamed and infected. Acute sinusitis usually lasts about 1-4 weeks, while chronic sinusitis is diagnosed when symptoms last three or more months. The third form, recurrent acute sinusitis, occurs more than three times a year.
Although sinusitis may begin during or after a viral infection, the condition itself is usually due to a bacterial infection or allergic conditions.
Acute infectious sinusitis may be caused by any number of bacteria, including:
- Hemophilus influenzae
- Streptococcus pneumoniae
- Moraxella catarrhalis
- Staphylococcus aureus
- Streptococcus pyogenes
These are all bacteria that are often found in the nose and throat of healthy people and which cause other common conditions, such as bronchitis and ear infections .
Certain other bacteria and fungi, such as Aspergillus, can be a cause of chronic sinusitis.
There are three main factors that predispose a person to developing sinusitis:
- Blockage of the small openings that run between the sinuses and the nose
- Malfunction of the tiny hairs (cilia) that are responsible for moving mucus and organisms out of the sinuses and nose
- Overproduction of mucus
Sinusitis is an extremely common problem. In a given year, about 37 million Americans suffer from sinusitis.
: image/18 "Paranasal Sinuses" center : image/19 "Sinus Infection" center
Alho OP. Vital infections and susceptibility to recurrent sinusitis.
Curr Allergy Asthma Rep.2005;5:477-481
Rakel RE, Bope ET.
Conn’s Current Therapy.54th ed. Philadelphia, PA: WB Saunders Company; 2002.
Sinus infection (sinusitis). National Institute of Allergy and Infectious Diseases website. Available at:
. Accessed September 12, 2008.